Is a dimmer noisy when it's turned OFF?

Thanks, Elizabeth. Great to know.

Anyone know of any dimmers that are not noisy? I'm guessing no, but would be nice to add the flexibility to my listening room if it exists. Also, if there is such an animal, what types of bulbs lend themselves well to dimming without being noisy/buzzing? Would LEDs work well if they're dimmable? Not going the halogen route. Others?

I have halogens on dimmers, and yes they caused hell with my system when i had them "on". The level of buzz and hum introduced into the sound varied with the amount of dimming used. It was VERY audible. Lutron, and Leviton both make a nifty gadget called a "de-buzzing" coil. I believe it's called a coloital coil or something like that. Mounts anywhere, wires inline between the dimmer and the power source. My problem was solved! They run about $100 and are worth their weight in gold. Absolutely NO noise whatsoever no matter how high (or low) the lights are dimmed. (I have 800 watts of halogen bulbs on track lites to illuminate my art work, and not a peep out of lites or stereo.) Lamps Plus sells these "de-buzzing" coils. And NO, you should not get any noise in your sound system if the dimmers/bulbs are completely turned off. Only when they're on do the seem to cause problems. Good luck.